Many devices, such as lawn mowers, weed trimmers, leaf blowers, and the like, are powered by hydrocarbon fuel burning engines. Due to their relatively high volatility, hydrocarbons quickly vaporize from the liquid fuel. Such hydrocarbon vapors can escape to the atmosphere from a fuel tank or other fuel system components. Increasingly, the evaporative emissions of such devices are being strictly regulated by various governments and agencies. Large, costly fuel vapor venting components and storage systems typically are not practical for small engine applications.